Some scientists have suggested that the longer the flagellum the more likely the sperm is to fertilise the egg cell.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

wild parsnip is a perennial plant which reproduces rapidly in areas which have no sign of agricultural activity such roadside or at no tillage open areas. it's considered invasive because it can inhibit the growth of another plant  and its reproduction is fast. there are several harmful effects of this invasive plant although its taproot is edible since it is a member of the carrot family. wild parsnips can cause skin blistering when in contact because of the chemicals it contains, second it inhibits the growth of other plants, it will restrict the growth of animals when eaten and lastly, it drives away natural pollinators like bees.